College of Engineering University of Wisconsin-Madison
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BME MONITOR: The Biomedical Engineering Department Newsletter


Fall/Winter 2005
Featured articles

Department receives W.H. Coulter tran slational partnership award in BME

Unlocking the brain

Learning clinical research

Microfluidics offers new portals for discovery

It's no shock: Tasers may be safer than bullets

Teaching clinic-based neuroengineering

Biology and engineering at UW-Madison: A student's landscape

Yongmin Kim receives College of Engineering Distinguished Achievement Award on Oct. 21, 2005

Regular Features

Message from the chair

Faculty news

In the news

Student news

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It's no shock: Tasers may be safer than bullets

Decorative initial cap In just a few seconds, a Taser delivers rapidly pulsed current that contracts recipients' muscles and temporarily "paralyzes" them. "It's designed to pass electric current through the body, which causes contraction of the muscles," says Professor Emeritus John Webster. "When this occurs, a person who's standing can no longer stand because their muscles contract, they're not balanced anymore, and they fall to the ground."

Law-enforcement officers often use the dart-firing device to subdue potentially dangerous or fleeing suspects, rather than injuring them with bullets. Its use, however, is under fire: Some groups allege that within the past few years, more than 100 people have died after receiving Taser shocks.

Although a January 2005 peer-reviewed paper in the journal Pacing and Clinical Electrophysiology showed the devices have a safety factor of 20 — in other words, it would take 20 times the current delivered to actually electrocute someone — two of the authors are employees of Taser International and critics question the results' validity.

An expert in electrical conduction through the body, Webster is conducting one of the first independent investigations into whether Tasers are, in fact, a safer alternative to bullets. His study, funded with $500,000 from the U.S. Department of Justice, aims, initially, to determine if the devices directly electrocute the heart.

Webster and his students developed computer models that show the most dangerous locations for Taser darts are those closest to the heart. They are determining the distance from the skin to the heart, which varies based on a personís size and weight. Conducting controlled tests on anesthetized pigs (which feel no pain), they are testing their models and determining how much electricity is required to electrocute the heart.

Webster's hypothesis is that Tasers do not directly electrocute the heart; thus, to learn more about why Taser-related deaths occur, he is studying if cocaine use is a contributing factor. During their tests, he and his students also are taking regular blood samples from the pigs to determine if blood chemistry changes — most notably, a surge in potassium due to muscular contraction — could play a role in the deaths.

When you have a strong muscular contraction, says Webster, the muscle breaks down, although the body's natural healing mechanisms enable it to heal again. "As the muscle breaks down, potassium goes into the blood, and if this happens enough, the person will die," he says, citing runners who collapse and die after overexerting themselves during a marathon.

The potassium surge is a condition that, if detected early enough, can be treated with drugs. Webster hopes that his group's results might make law-enforcement and emergency-room personnel more aware of potential complications from a Taser shot. "We might have some suggestions to emergency room physicians in situations like this, which might save some lives," he says.

Based on the tests he and his students currently are conducting, Webster also plans to develop Taser testing protocols, similar to the safety standards applied to testing new power-line equipment. "One of my goals is to develop a standard that will be recognized for testing Tasers and similar devices on the bench, in the same way that power-line devices are tested on the bench," he says.

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Copyright 2005 The Board of Regents of the University of Wisconsin System

Date last modified: 22-Dec-2005
Date created: 22-Dec-2005



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